Fluorocarbon-azomethines



Patented June 23, 1953 UNITED STATES PATENT OFFICE 2,643,267 FLUOROCARBON-AZOMETHINES Willi'ur Fearlson Whitc Bear Township, Ramsey County, and Lyle J. Hals, St. Paul, Minn.,

assignors to Minnesota Mining & Manufachiring Company, St. Paul, Minn., a corporation of Delaware N'o Drawing. Application January 28, 1950, Serial No. 141,164

4 Claims. (Cl. 260*566) ce-ir t I 1 of previously known compounds containing car-- bon, fluorine and nitrogen, plus one or more other elements.

It will be seen that the carbon-fluorine nitrogen compounds of our invention, described and claimed herein, are to be distinguished from all the prior known compounds just mentioned. Also, as will presently be more fully illustrated, the compounds above mentioned, disclosed in We have found that compounds of the type the Kauck and Simone application Serial No. just named, especially those having the formula 5 illustrate t y fluorocarbon amines 0f CeF2n+1N, in which n is a whole number of 2 or w p contmplated by us f as starting higher, are of considerable value. For example materlals in making F unsaturated they may be employed as intermediates in the Compounds, i W Q' n s a whle u r either production of further chemical compounds, such 2 or m r up 5? compounds wnlch as fluorocarbon acids, e. g. CFsCOOI-I, CtF5COOH W are Pmi ul y Interested are those m Whlch and other CnF2n+1COOH acids, where a is any n an nt e 9 2 9 I integer, and secondary amines, e. g. (C2F5)zNI-I, Qf Q bQPj PQ QTmF fQ E Compounds having the general formula (CnF21i-H)2NH. Our general Include the followmg structure carbon-fluorine-nitrogen unsaturates also pro- 20 vide interesting and useful source materials in JOgN-Ql}; the production of polymers including carbon, 1 l g r t ir i i m p gfifi ds hav ng carbon fluorine Where. free vaiepces Shown 9 and nitrogen joined together in the same mole- 25 carbon orifiuorme i' in W111 n that cule have been known prior to this invention Compounds of sue-h i WWW 2231i?1 33 3355iftitihififitif e eg g @3 .geee e er now abandoned in favor of continuing application ig i e i i th t ggf ai ie S r al No 61717 filed May 12 1951'. An ex- 9 P 5? imi i ".5 E9. 5, i f r amp erfluorotri trated also yield iiuorocaroon olefins, having the giiakfi la y 1 p general formula 011F211, or which CFQCF} ,C!FB(F1G=CECFQ) cream-reorient 35 Other examples of carbon-fluorine-nitrogen com and w m I pounds are disclosed in U. S. patents of Joseph fl' s fl fl eFi) H. Simons NOS. 2,490,098 and 2,490,099, bOt'h granted December 6, 1949. Additionally certain 40 are exampjes other carbon-fluorine-nitrogen compounds have r v been known in the prior art, but, to the best of F i can produce our our knowledge none of the type herein described p 16 car 'm mgen compounds frQ-m and claimed Further some compositions have tertiary fluorocarbon amines by (a) heat decom; been referred to as containing compounds of position (b) decomposition at elevated 5 carbon, fluorine and nitrogen, but s'uch peratur'es in the presence-of acatalyst. In other pounds are so different from the compounds of Words We h dlscoverefi at We may produce this invention and so unstable that, upon reac- 9 compounds 9 1711? ternary fi aI-bOD tion with ammonia, nitrogen is liberated as a fi y FY 5 M OI catalytic conversion of gas. CFsCHzNHz and CFeCONI-Iii are examples 0 the as hereinafter illustrated. The idl lowing equations illustrate the production of our novel compounds:

A (CFsCF2CF2)aN CiFtN CaFu C1Fo and catalyst) The particular reaction compounds which we obtain, as is illustrated hereinafter, depend upon the reaction conditions, including the nature of the catalyst, if any, as well as upon the starting materials. For example, depending upon the nature of the catalyst employed (where one is employed), we either produce C4F'9N or CsFnN, where (CF3CF2CF2)3N is the starting material.

Both the C4F9N and the'CaFisN are aliphatic compounds and involve the structure In the equations just illustrated above it will be understood that the A symbolizes heat decomposition, which may, for example, be carried out at temperatures of the order of 600 to 800 C. The reference to catalyst in connection with the equation last shown above symbolizes a catalytic decomposition reaction, also carried out at elevated temperatures although, because of the catalyst, the temperature may be lower than in the straight pyrolytic reaction. Also, depending upon the nature of the catalyst used, the results of the reaction may be modified and the reaction products may be caused to differ in molecular weight and structure.

Having described the broad outlines of our invention and illustrated it in certain respects, we will now point out, by examples, just how our novel process may be carried out and how our new compounds may advantageously be produced.

First we will describe the equipment and general conditions employed by us in the thermal decomposition of tertiary fluorocarbon amines to yield our desired products.

Equipment and general procedure A 16 inch section of graphite tubing of inch inside diameter, within a close-fitting iron pipe which served as a protective support, was heated by us over a 12 inch section in an electric furnace. The temperature was measured by means of a Chromel-Alumel thermocouple placed between the iron pipe and the lining of the furnace. Liquid fluorocarbon was introduced into the heated chamber by allowing it to drop at a steady rate from a separatory funnel into a section of the inner tube which was heated sufficiently to vaporize theliquid. The vapors were swept into and out of the reaction tube through close-fitting steel adapters with a stream of nitrogen gas.

The exit gas was condensed in a series of traps cooled successively by ice, Dry Ice-acetone, and liquid air. The condensate was then passed over sodium fluoride at 100 C. to free it of traces of HF. No other chemical treatment was given the reaction products before isolation and purification.

The product boiling below room temperature was fractionated through a vacuum jacketed column packed with inch single turn stainless steel helices. The product boiling above room temperature was fractionated through a glass helix packed column with a head cooled by ice water. Compounds were identified by their physical properties and other characteristics.

Employing the foregoing equipment and general procedure, a number of specific reactions were carried out by us, of which the following are illustrative Example 1 154 grams of tris(pentafiuoroethyl) amine, i. e. (C2F5)3N, was passed through the usual graphite tube at a flow rate of approximately .05 mol per hour, with an equi-molar quantity of nitrogen. The reaction tube was kept at 745 C., at which temperature about of the starting material was decomposed.

The principal products of reaction were (a) C3F'1N, l. e. CFsCF2-N=CF2, (b) CsFa, i. e. CF3CF=CF2 and (C) C2F4, i. e. CF2=CF2.

However the reaction products also included, in lesser quantity, the saturated compounds C2Fa and 031%. Also, as above indicated, about of the starting material, (C2F5)3N, was left undecomposed.

The foregoing ingredients were separated by fractional distillation and identified. For example, the C3F7N was identified as boiling within the range of 18 to -13 C. (about 13.2 C.) and having a molecular weight within the range of 180-184. The weight of the C3F7N fraction was 15.0 grams.

The 'CaFqN fraction was further identified by infrared analysis; its infrared spectrum exhibits a strong band at 177.0 cm. which is characteristic of unsaturation. However the compound did not absorb bromine at room temperature, which indicates that the unsaturation is not of the carbon-to-carbon C=CF2) type.

Upon treatment of the carbon-fiuorine-nitrogen fraction, 1. e., the CFN fraction, with an aqueous alkali in a closed, evacuated system, a vigorous reaction took place, with evolution of a gas, which latter dissolved in the solution when an excess of alkali was added. The solution, upon analysis, was found to contain equi-molar quantities of NH3, CO2 and CFsCOOI-I, i. e. trifluoroacetic acid. The trifluoroacetic acid was definitely identified by its boiling point (approximately 72" C.) and infrared spectrum.

The C3F7N compound apparently hydrolyzed according to the following reaction:

The formation of the trifluoroacetic acid, CFSCOOH, from the C3F7N compound lends still further evidence that the CaFIN compound contains the structure -o=N-e l l as a part of its entire molecular structure The characteristic of our compounds which contain the structure C=N(I3 l I by which upon hydrolysis they form trifiuoroacetic acid, CFsCOOH, and/ or higher fluorocarbon acids, is one of their unique and valuable characteristics.

Example 2 275 grams of tris(heptafluoropropyl) amine, i. e. (C3F7) 3N, was passed through the previously described graphite tube, at a flow rate of .05 mols per hour, with an equi-molar quantity of nitrogen. The reaction tube was kept at 660-6'70 C. The following compounds were obtained (upon separation of the reaction products by distillation) V Moles of Product per 100 Moles of Starting Material Decomposed CF; 2 2F4 4 C2Fs l 4 C5Fg. 25 C3F5 19 04F) 24 CAFE; 1 C4FQN 73 Higher boiling fractions. 35

From the foregoing it will be seen that, for each mol of starting material, i. e. (C'3F7)3N, decomposed, 0.73 mol of C4F9N, i. e.

was produced. Said compound had a boiling point of 12.3 to 125 C. This compound was also identified by tests as generally described in EX- ample 1. Also, upon hydrolysis, with an aqueous base, it was found to yield penta'rluoropropionic acid, i. e. CFsCFzCOOH.

Example 3 :66 grains of tris(nonafluorobutyl) amine, i. e. (CrFehN, was passed through the previously de scribed graphite tube at a flow rate of .04 mol per hour. The reaction tube was kept at a temperature of 645-650" C. The following com= pounds were obtained, upon separation of the reaction products by distillation.

Moles of Product per 100 Moles of Starting Material Decomposed Low boiling O1 and 02 compounds CaFs.

For each mol of the starting material, 1. e. (CQFUEET, decomposed, it will be seen that 0.77 mol. of C5F11N, i. 8. CF3(CF2) 3N='CF2, boiling at 39.0 C., was produced. This compound (alsoidentified by tests as above described) was hydrolyzed in an aqueous alkali to give a 93% yield of CsFrCOOI-i, i. e. heptafiuorobutyric acid.

Example '4 The following compounds were obtained, upon separation of the reaction products by distil1ation:

Moles of Product per Moles of Starting Material Decomposed CF; 1 021% 1 CgFu. 2 O3Fg 13 C3F@. 13 0 F 33 C4Fs 1 OiEaN..- 100 C5F12.. l- 30 Higher boiling fractions 23 For each mol of the (carom starting mate rial, it will be seen that the reaction yielded 1 mol of 0mm, i. e. CFaCFzCFzN'=CF'2, boiling at 12.3 to 12.5 C. That is, this gave a 100% yield of CiFQN on the basis of the starting material decomposed.

As compared with Example which lacked the catalyst here employed, the present example shows a decrease in C1 and C2 fiuorocarbons' and an increase in C4, C5 and Cs fluorocarbons.

Tests, as above described, were employed in identifying the CF3CF2CF2N=CF2, i. e. the C4FQN, as well as other compounds above listed.

Example 5 315 grams of (C3F7)3N was passed through the previously described graphite tube, but in this case packed with dry sodium fluoride pellets. The tube was maintained at a temperature of 660-665 C. The flow rate and other conditions and procedure were as described in Example 4.

The following compounds were obtained:

For each mol of the (CsFmN starting material it will be seen that the reaction yields 0.82 mol of CiFsN, i. e. CF3CF2CF2N=CF2, boiling at 12.3 to C. That is, this gave an 82% yield of C4F'9N on the basis of the starting material decomposed.

It will be seen that the sodium fluoride catalyst of this example changes the distribution of products as compared with Example 2, although the change is not as marked as in the case of the aluminum .fluoride packing.

.Ezmmple 6 Completely fiuorina'ted diethyl propyl tertiary amines, i. e. (CzE5)zNCsFr, when treated under conditions as above illustrated, were found to yield (in addition to saturated and unsaturated fluorocarbons) a plurality of compounds each having the important structure AFNWL above referred to. Where .(CzFshNCaFvisthus 7 decomposed, CF3CF2N=CF2 (boiling at -13.2 C.) and CF3CF2CF2N=CF2 (boiling at 12.3 to 125 C.) were produced, each having the structure With diflerences in the tertiary amine start-.

ing materials, corresponding differences in the carbon-fiuorine-nitrogen products, containing the structure, will result. For example, where a completely fluorinated dipropyl ethyl tertiary amine is employed as the starting material, the carbonfiuorine-nitrogen reaction products are also CF3CF2N=CF2 and CF3CF2CF2N=CF2, but their relative proportions are the reverse of those where the completely fluorinated diethyl propyl tertiary amine is employed as the starting material, as just indicated above.

This will serve to illustrate further how the carbon-fiuorine-nitrogen products vary with differences in the completely fluorinated tertiary amine starting material.

Example 7 628 grams of (C2F5)3N, which was also used in Example 1 hereof, was passed through the previously described graphite tube, at a flow rate of 0.15 moi per hour, using nitrogen as a carrier. As distinguished from Example 1, in this case the graphite tube was packed with an aluminum fluoride-aluminum oxide catalyst, prepared by partially reacting alumina with hydrogen fluoride. The packed tube was maintained at sec-550 C.

In addition to saturated and unsaturated fluorocarbons, upon fractionation a compound of the formula CiFsN was obtained, the same having the structural formula CF3CF2N=CFCF3 and boiling at 13.0 to 13.5 C.

It will be seen that the carbon-fluorine-nitrogen reaction product in this case is different from that of Example 1, having a difierent molecular weight. Also, although the empirical formula, CiFeN, is the same as that of the carbon-fluorine-nitrogenreaction product of each of Exampies 2, 4, 5 and 5, yet infrared analysis indicates the product of this example to be readily distinguishable from the corresponding products of the other examples. Furthermore, upon hy- (irolysis, two mols of perfluoro acid (trifluoroacetic acid) are obtained from one mol of the C4F9N product compound of this example,

In addition to the evidence of the structure, F3CF2N:CFCF3, provided by the hydrolysis, we also found that bromine is not absorbed at room temperature, which indicates (see Example 1) that the unsaturation is not of the terminal carbon-to-car'oon type.

The relatively low temperature employed in this example, coupled with the use of a catalyst, provides our explanation of the important difference in the C4F9N product compound.

Example 8 Using the same apparatus and procedure as employed in Example '7, we employed, however, (C3F7)3N as the starting material,

In addition to saturated and unsaturated fluo-. rocarbons, we obtained the compound CeFisN, boiling at 56.5-57.5" C. and having the structure CF3CF2CF2N=CFCF2CF3.

This product compound was identified by tests previously described herein and, like the C4F9N product compound of Example 7, upon hydrolysis yielded 2 mols of perfluoroacid (pentafiuoropropionic acid) per mol of the said CGFIKN compound.

It will also be noted that, as in Example 7, the structure of this CsFisN compound is widely different from compounds shown in earlier examples, in that it has such a structure that upon hydrolysis two mols of perfluoro acid are produced for each mol of the CGFISN compound, that is, for each mol of the product compound havlng the structure In addition to the productions above described, in Examples l-8, we also carried out several larger scale preparations, in which We successively produced several hundred grams of each of the following compounds:

Upon reaction of the CaF'zN, as produced in Examples l and 6, with HP at a temperature of about C., the HF adds on, the H becoming bonded to the N (as shown by infrared analysis). thus yielding a perfiuoro secondary amine, i. e. CFsCFzNHCF'a. This addition reaction further demonstrates that compounds of this type, made up of carbon, fluorine and nitrogen have a double bond joined to the N.

Hereinabove we have referred to various fluorocarbon tertiary amines as the starting materials for our reactions. These tertiary amines may be referred to generally as (R-f)3I T, Where R: stands for a perfluoro hydrocarbon group and each Rf group may be the same or different. Each B: group contains a carbon atom joined to the nitrogen.

Also hereinabove we have disclosed various compounds of carbon, fluorine and nitrogen which contain the structure where the free valences are satisfied by fluorine or by perfiuoro hydrocarbon groups. It will be understood that compounds of this type, in addition to those specifically named, are also contemplated.

Other novel embodiments and variations in products and methods will readily occur to chemists skilled in this art, in the light of the descript1on and examples herein contained. All such embodiments and variations, as Well as those herein specifically set forth, are likewise comprehended within this specification.

What We claim is:

1. An organic compound having the empirical formula CnF2n+lN and containing the structure C=N t I I where n is an integer of at least 2.

2. An organic compound having the empirical formula CnF2n+1N and containing the structure C=N n being an integer from 2 to 20.

9 3. A compound of carbon, fluorine and nitrogen having the structure RrN=CF2, where R: denotes a perfluoro alkyl radical.

4. A method of producing organic compounds having the empirical formula CnF2n+1N and containing the structure which comprises heating a perfiuoro alkyl ter- 10 tiary amine to an elevated temperature Within the approximate range of 400 to 800 C., so that new products are produced having the empirical formula CnF2n1-1N, and containing the structure 10 Where n is an integer of at least 2, all of the fluorine of the molecule being bonded to carbon atoms, and separating the C1LF2n+1N compounds from the remainder of the reaction mixture.

WILBUR, H. PEARLSON. LYLE J. HALS.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Rigby et a1 Oct. 15, 1946 Number 

1. AN ORGANIC COMPOUND HAVING THE EMPIRICAL FORMULA CNF2N+1N AND CONTAINING THE STRUCTURE 